Printing device



l. GuRwlcK PRINTING DEVICE Filed Aug. 3, 1939 April a, 1941.

2 Sheets-Sheet 1 INVENTQR.

@ya/cm @lfm ATTORNEYS April 8, 1941. l. GuRwlcK 2,237,349

PRINTING DEVICE Filed Aug. 3, 1939 2 Sheets-Sheet 2 Q INVENTOR. A

ATTORNEYS.

Patented Apr. 8, 1941 UNITED [STATES PATENT .or-*FICE PRINTING DEVICE Irving Gurwck, Mount Vernon, Qhio, assigner to Shellmar Products Company, Mount Vernon, Ohio, a corporation of Delaware Application August 3, 1939, seriarNo. 238,185

(ci. 11u- 157) l Il Claims.

The present invention relates to an improved color unit of the type employed in intaglio ma;- chin-es, and has particular reference to an improved inlr applicator designed for use with intaglio printing units having a relatively high printing speed.

intaglio printing units generally consist of a color bath in which rotates a conventional etched printing cylinder, the excess ink taken up by the printing cylinder being removed by a doctor blade before contact of the printing cylinder with a web to be decorated. Where the printing operation is to be done upon surfaces such as those 'afiorded by transparent cellulose sheeting, difficulty citen is encountered in properly supplying the etched portion of the printing cylinder with an adequate supply of ink, particularly at high speed.

A principal object of the present invention is the provision of an improved ink applicator for use with intaglio printing machines, in which an adequate supply of ink rto the etched printing cylinder is insured at all speeds, even at relatively high speeds.

Another object is to provide an intaglio ink applicator in which ink is overflowed through a gap formed between the cylinderand a longitudinally extending ledge or wall of an overflow trough positioned so that the overhanglng portion of the cylinder with respect to the trough is above the overflow ledge, the trough preferably being sufficiently narrow that less than one quadranrt of the cylinder will be in contact with the l ink in said trough.

Still another object of the invention is to provide an ink applicator for uniformly overflowing ink against the downwardly turning side of an etched printing cylinder regardless of the speed at which the cylinder is turning.

These and Iother objects will be evident upon a considera/tion oi the following specification, and by reference to the accompanying drawings, in which-L Fig. 1 is a side view of a device constructed in accordance with my invention;

Fig. 2 is a sectional view taken `along line 2-2 oi Fig. 1: andl Fig. 3 is a. fragmentary detailed sectional view taken along line 3-3 of Fig. 2.

The conventional form of ink applicator for intaglio printing presses consists of a, tank-like color bath in which rotates an etched cylinder. As the etched cylinder passes through the ink contained in the color bath the ink adheres to the cylinder and prior to the printing operation the excessink subsequently isremoved by a doctor mechanism. A great deal of diiliculty has been encountered in uniformly applying ink to the cylinder when the press operates at relatively high speed. Various types of special ink; applim cators including maniiold'and Apressure devices have been devised, but due to the delicacy oi' adjustment necessary and to the different oper ating conditions of the press, including such iactors as printing cylinders of varying sizes. these special types of ink applicators have not met with success. i A

The construction of the present invention is shown as including an open, longitudinally extending ink or color tank or bath ill which may be of' conventional shape and construction. Within this color bath rotates an etched printing cylinder i I. As will be seen in Fig. 2, an impression roll i2 is mounted on .the side of the printing cylinder so that the printing line is within the first quadrant of the printing cylinder. The course of Ithe web to be printed is also indicated in this iigure, the web being shown at I3. This web passes downwardly from the ieed roll, or

from the preceding color unit, through the colorunit shown and then passes upwardly to the next color unit after .the ink has dried.

The color bath l0 has mounted at each of its ends the overflow pipes Hi, these pipes, being situalted beyond the ends of the cylinder il. The tops of the pipes are provided with flanged sec` tions i5 through which pass the adjustment screws I6, the latter having their .ends resting upon the bottom of the tank I0.

Thedownwardly extending overflow pipes I4 pass through sleeve sections il which depend from the bottom of the color unit I0. The sleeves l1 and overflow member I4 deliver excess ink from 4the -tank lll .to a reservoir to be described hereinafter. By :turning the screws i6 it will be seen that it is possible vto make an accurate adjustment of the ink level within the tank I0. As shown in Fig. 2, the bottom of .the sleeves I1 have attached to them the flexible hoses idf by which the excess ink is .transferred back to the ink reservoir. The tank IU may be carrled`\ in any suitable framework such as the members I8 shown in the drawings.

The ink normally employed in intaglio prining machines is of the quick-drying type in which the body of the inkis carried in a highly volatile solvent such as benzol, toluol, and the like. The inks most suitable for printing transparent Vcel,- lulose sheeting are lacquer inks in which the body of the ink is composed of a'cellulose -derivativef such as cellulose nitrate and a resin. Suitable plasticizers may be employed to impart the desired flexibility to the ink. The ink may carry a soluble or insoluble pigment of any desired color.

Since an intaglio cylinder contacts the entire area of the web to be printed the previously deposited color is dried before the web reaches ,the next adjacent color for applications of fresh ink of the same or a different color. In high speed presses this has led to an increase in the vola-L tility of the solvents employed inthe process. It

-has been suggested to enclose the ink fountain in order to prevent loss of solvent by evapora-` 'tion and a consequent increase in the density of l the color. This leads Ito complicated construction which I have found can be avoided 4by suspending beneath the color bath a cooling chaming eect of. ink spilling over the baiie against the side of the printing cylinder,

The printing cylinder itself forms a dam or wall which provides a gap between the cylinder and the overiiowltrough below the level of ink in the latter, and ink in the trough contacts the printing cylinder above the overflow baille. The

l frictional engagement of the cylinder with the ber indicated generally at 20, this cooling chaml is supplied between the sections and 23.

The bottom of the color bath I0 is provided i with a longitudinally extending plate 21 on the side of the tank adjacent the downwardly turning side of the cylinder Ii, this plate being suit- 'ably brazed or otherwise attached to the color bath I0. At spaced intervals along its length the ink increases the overflow between'the baille and cylinder as the latter rotates more. rapidly.

thereby insuring an adequate and, sufilciently uniform ink deposition in the cylinder.

In Fig. 2 there is shown a shield 36 which extends between the conventional doctor mechanism 31 and the printing line. The doctor mechanism 31 removes excess ink from the printing cylinder and` the volatility of the ink is such that under certain conditions substantial amounts of the solvent will evaporate from the etched portions of the cylinder between the doctor blade and the printing line. The shield 38 iits closely adjacent but spaced from the printing cylinder so as to provide a solvent atmosphere which will inhibit loss of solvents by the ink prior to application of the ink to the web to be decorated.

In the operation of the device an initial step consists in starting the pump 32 and pumping n relatively large volume of ink into the trough between the baiiies' 33 and 34. If the machine is operating slowly the amount of ink will be more than can fiow over baille adjacent the printing cylinder and the excess ink will iiow over the baille 33 to be returned through the overow line plates 21 in the bottom of the tank are supplied v with openings through which extend the inksupplying couplings 28. The couplings 28 have branch lines '29 communicating with a common supply line 3D, which may be a exible hose, leading to an ink reservoir 3| through a pump 32;

In color units of the type described hereinbefore the rapidly rotating cylinder tends to form a hollow spot between the cylinder and ink so as to prevent the cylinder from picking up anadequate supply of ink. Inferior printing is the direct result of this inadequacy. I have found ythat the fault may be remedied by supplementing or substituting for the conventional color bath a small overflow trough positioned in such a manner as to provide an underlying overflow gap with the cylinder, as will be described.

An upwardly extending baille plate 33 is mount- 4 ed on the floor of the tank i@ along the outside of the openings through which connections 23 extend. It is preferred that the upper portion of the baiiie plate 33 be turned over, as shown in Fig. 2. The turned-over portion of the baille plate 33 is spaced substantially from the printing cylinder and the upper portion of the baiiie extendsupwardly somewhat above the normal ink level in the tank i0. 'I'his turned-over portion acts as a means for more uniformly distributing in the overflow trough the ink which is pumped into the trough through the spaced connections 28.

On the opposite side of the ink supply sections 23 from the baille 33 is mounted a second baille 3l having at its upper portion a plate 35 constituting an overflow member which extends on an angle downwardly toward the printing cylinder Il. It is of importance to note that the end of the baille or overiiow plate 35 is spaced from the printing cylinder Il so as to insure an overflow'- to the ink reservoir. This provides a constant 'level for the ink in the applicator trough as weil as in the color bath i0 and an unlimited supply which needs no adjustment or care.. The baille 35 affords an overflow of ink directly against the side of the printed cylinder on its downward travel. By adjusting the distance between the end of baille 35 and the printing cylinder it is possible to get any desired flow of ink from the applicator trough into the color bath I0. Thus, where a large flow is not desired it is sufficient to 4 provide a clearance between the baille 35 and the printing cylinder of the order two one-thousandths of an inch. In some cases'a larger opening will be desirable and this opening between the baffle 35 in the printing cylinder may be as much as one-eighth of an inch, or more.

It will be seen that the liquid level in the aps plicator trough between the bailies 33 and 34 is higher than the liquid within the tank I0. This insures a uniform overflow of ink between the printing cylinder Il and the bame 35 and uniform application of ink to the entire length of the cylinder regardless of the speed of the cylinders rotation. As the rotation of the cylinder increases in speed, less of the ink will overflow the baiile 33 and more of it will be taken up by the printing cylinder. The applicator trough is open to the atmosphere so .that pressuredoes not develop therein.

The overflow characteristics provided by a mechanism of this type have been found highly desirable in intaglio printing presses of the type employed in printing transparent cellulose sheeting at high speeds. For example, at speeds of 600 feet per minute an ordinary intaglio ink trough is inadequate to provide uniform color distribution, possibly due to the centrifugal effect of the printing cylinder as it passes through the rotating bath of ink. The ink is thrown away from the cylinder as to prevent adequate adherenece. The overflow type of applicator described herein amanece 4of the amount of ink supplied to the applicator trough is required. There is not incurred the danger of inadequate ink application by reason .oi changes ofv pressure or other factors.

It will be noted that the printing cylinder still rotates in a bath of ink in the coloxwbath Il), but the ink withinthe bath Il) does not affect the application to the printing cylinder.` It functions as an overow reservoir for the applicator trough. Location ofthe applicator trough and the overilow baiiie 35 on the downwardly turning side of the printing cylinder results inthe latter assisting in the overflow function and the application of the ink. Thus, `at higher speeds the printing cylinder may have an increased efdciency of application of ink. In many cases it will be found desirable to entirely eliminate the tank I and to reciroulatethe overflowing ink directly to andrrom a separate reservoir. Also, the position of theoverfiow-trough may be changed from that shown in the drawings. In other positions the lowest portion of the cylinder in contact with the body of ink in or above the trough will still be above the overow ledge or the trough, and the trough will be suiflciently small as to provide an ink Supply contacting less than one quadrant of the printina cylinder. The overflow ledge of trough is on its lower side, as will be noted in the drawings.,

lit will be` recognized that many changes may be made in the invention as described herein for .purposes of explanation, and such changes are intended to be included in the appended claims.

l. lin a device of the type described, a relatively narrow overflow trough having a substatitially horizontal overow ledge, means for supplying inl; to said trough, means for distributing the ink in the trough, and a rotatable cylinder overlying the trough and forming an overflow gap with said ledge, the lowest portion of said cylinder overlying said'trough being above said ledge. t

2. An intaglio printing unit, comprising a color bath. 'an etched printing cylinder rotating in said color bath, an overow trough having a relatively high wall and a relatively low overow wall forming an overflow gap with said printing cylinder on the underside thereof, means for receiving ink after it hasoverilowed from said trough, means for returning the inl; to a reservoir. and means for circulating ink between said reservoir and said trough; that portion oi' the cylinder spanning the walls or said trough being above the overflow 'portion oi said low wall, and said trough being suiiiciently small to provide inn contact with less than one quadrant of the area of said cylinder.

3. An intaglio printing unit, comprising a color bath, means for controlling the level of liquid in said `color bath, a printing cylinder rotating in said color bath. an overow trough in said color bath on the downwardly turning side oi' said cylinder. said trough having an overflow plate helow the liquid level in Isaid color bath and entending adjacent but spaced from said cylinder and a second plate extending above the liquid level in said color bath, and means for supplying a higher head or ini: in said trough than in said tanlr.

An intaglio printing unit, comprising a color bath provided with liquid level maintaining means, a printing cylinder rotatably mounted in said color bath with its lower side below said means, and an overow trough adjacent said cylinder below its anis and on the downwardly turning side thereof, said trough having a downwardly inclined overflow ledge below said means.

V- IRVING GURWICK. 

